Dumbbell rows would fit in nicely with Day 1 (shoulders/back). I'd sub them in over a machine-oriented row, which is consistent with your focus on dummbell exercises to build stabilizers.

I don't see any plyometrics in your routine, which would help you with the explosive twisting and pulling movements inherent in tennis (serves, forehands, backhands). I'd take out some of the dumbbell presses and fit in more medicine ball trunk twists, etc.

It's a good split. If you want to do bar rows then just add them in. To lighten your first day and accommodate bar rows then take out upright rows. I used to do them but they're terrible for the shoulder joint.

Also, chins and lat pull downs are essentially the same motion. If you're unable to do chins unassisted then just stick with pull downs. You can do close or wide grip variations of it.

I skip decline bench as well. Not really necessary. Overall it's a good routine, though definitely add deadlifts. Personally, I never do dips and bench on the same day. I like to be fresh for dips. I do dips on arm day.

If you're lifting to be tennis specific...it seems like that's a lot to me.

I am no expert on lifting so please don't take my advice directly to heart, but my days are much shorter than that at a high intensity...and my results are great.

Also...the leg workout you have a good one to build solid muscle...but not much of it is "tennis specific". You should be doing linear lunges, lateral lunges, crossover lunges, etc. Think of what your specific movements are on the court and how you need to make them better, and then work on a lift that will make that action better.

You could probably get rid of a few things, like dumbbell front raises (those are used as sort of a finishing touch by bodybuilders, not for strength training), and maybe instead of doing leg press, just focus your energy on doing more sets of squats. And maybe think about doing less reps and heavier weight for some of the exercises, like 6-8.

Also, your anterior deltoids are getting worked out enough from all the other stuff, doing front raises will just help to create an imbalance and give you shoulder problems. Do rotator cuff work instead.

Not sure what weights you are using... I would consider going to slightly lighter weights and increasing reps. This will help tone, build strenght and mass. At the same time this will keep your muscles loose.